Silicone fine particles such as silica, polyorganosilsesquioxane particles, and the like, are widely used in various industries. Among these, polyorganosilsesquioxane fine particles are widely used as additives for resin or coating agents because of their good compatibility with polymer materials or organic solvents. Recently, polyorganosilsesquioxane fine particles have received attention as light diffusing agents for light diffuser plates in LCD-TVs, because of their low refractive index and good compatibility with resins. These silicone fine particles can be prepared by a conventional sol-gel process. The production cost, however, of the conventional sol-gel process can be high, because it requires expensive monomer and its yield per time unit is low.
Japanese Patent No. 1,095,382 discloses a method for producing polymethylsilsesquioxane by hydrolysis and condensation reaction of methyltrialkoxysilane having a chlorine content of 0.1˜5%. It can be difficult, however, to control the reaction rate in this process because of the high concentration of chlorine. Further, hydrogen chloride can intensify corrosion in the reactor, which can make its use impractical.
Japanese Patent Laid-Open Nos. 1998-045914 and 2000-186148 disclose a process for producing polyorganosilsesquioxane fine particles by hydrolyzing a mixture of water and methyltrialkoxysilane which does not contain chlorine in the presence of a catalyst such as an organic acid or an inorganic acid, and adding an aqueous alkaline solution thereto to effect a condensation reaction. These methods employ high purity methyltrialkoxysilane, which requires a separate refinery process, and need a hydrolysis catalyst. As a result, these methods can be expensive.